Device and method of performing codec rate adaptation in a wireless communication system

ABSTRACT

A communication device for performing a codec rate adaptation comprises a storage device for storing instructions and a processing circuit coupled to the storage device. The processing circuit is configured to execute the instructions stored in the storage device. The instructions comprise receiving a first bit rate recommendation from a first cell; selecting a first codec rate according to the first bit rate recommendation and encoding a first plurality of packets according to the first codec rate; receiving a handover command; performing a handover to the second cell in response to the handover command; transmitting a bit rate query to the second cell after the handover; receiving a second bit rate recommendation from the second cell; and selecting a second codec rate according to the second bit rate recommendation and encoding a second plurality of packets according to the second codec rate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Applications No.62/405,261 filed on Oct. 7, 2016, and No. 62/429,088 filed on Dec. 2,2016, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a device and a method used in awireless communication system, and more particularly, to a device and amethod of performing a codec rate adaptation in a wireless communicationsystem.

2. Description of the Prior Art

Voice and Video over LTE (VoLTE/ViLTE) are key features for long-termevolution (LTE) to provide voice and video service. Regarding a codecmode/rate selection and adaptation in the VoLTE/ViLTE, third generationpartnership project (3GPP) agrees that for the case of using the codecrate adaptation during an on-going call, from a radio access network(RAN) perspective, a RAN-assisted solution is beneficial and feasible.

SUMMARY OF THE INVENTION

The present invention therefore provides a communication device forperforming a codec rate adaptation to solve the abovementioned problem.

A communication device for performing a codec rate adaptation comprisesa storage device for storing instructions and a processing circuitcoupled to the storage device. The processing circuit is configured toexecute the instructions stored in the storage device. The instructionscomprise receiving a first bit rate recommendation from a first cell;selecting a first codec rate according to the first bit raterecommendation and encoding a first plurality of packets according tothe first codec rate; receiving a handover command configuring thecommunication device to hand over to a second cell from the first cell;performing a handover to the second cell in response to the handovercommand; transmitting a bit rate query to the second cell after thehandover; receiving a second bit rate recommendation from the secondcell, wherein the second cell transmits the second bit raterecommendation in response to the bit rate query; and selecting a secondcodec rate according to the second bit rate recommendation and encodinga second plurality of packets according to the second codec rate.

A communication device for performing a codec rate adaptation comprisesa storage device for storing instructions and a processing circuitcoupled to the storage device. The processing circuit is configured toexecute the instructions stored in the storage device. The instructionscomprise transmitting a bit rate query to a cell; and retransmitting thebit rate query to the cell, when not receiving a response for respondingto the bit rate query within a time period.

A communication device for performing a codec rate adaptation comprisesa storage device for storing instructions and a processing circuitcoupled to the storage device. The processing circuit is configured toexecute the instructions stored in the storage device. The instructionscomprise triggering a first transmission of a first Medium AccessControl (MAC) Control Element (CE) for a bit rate query or a delaybudget reporting, and a second transmission of a data; making a firstdetermination that a transmission priority of the first MAC CE is lowerthan a transmission priority of the data; allocating the data in a MACProtocol Data Unit (PDU) in response to the first determination; andallocating the first MAC CE in the MAC PDU, if a remaining space in theMAC PDU is sufficient for allocating the first MAC CE after allocatingthe data.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a wireless communication systemaccording to an example of the present invention.

FIG. 2 is a schematic diagram of a communication device according to anexample of the present invention.

FIG. 3 is a flowchart of a process according to an example of thepresent invention.

FIG. 4 is a flowchart of a process according to an example of thepresent invention.

FIG. 5 is a flowchart of a process according to an example of thepresent invention.

FIG. 6 is a flowchart of a process according to an example of thepresent invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a wireless communication system 10according to an example of the present invention. The wirelesscommunication system 10 is briefly composed of a network and a pluralityof communication devices. The network and a communication device maycommunicate with each other via one or more carriers in the same ordifferent duplexing modes (e.g., frequency-division duplexing (FDD),time-division duplexing (TDD) or flexible duplexing).

In FIG. 1, the network and the communication devices are simply utilizedfor illustrating the structure of the wireless communication system 10.The network may be an evolved Universal Terrestrial Radio Access Network(E-UTRAN) comprising at least one evolved Node-B (eNB) or a fifthgeneration (5G) radio access network comprising at least one 5G BS. The5G radio communication technology may employ orthogonalfrequency-division multiplexing (OFDM) or non-OFDM, a wide bandwidth(e.g., 100 MHz) and a transmission time interval (TTI) smaller than 1millisecond (ms) (e.g., 100 or 200 us) for communicating between withthe communication devices and the BS.

A communication device may be a UE, a mobile phone, a laptop, a tabletcomputer, an electronic book, a portable computer system, a vehicle, oran aircraft. In addition, the network and the communication device canbe seen as a transmitter or a receiver according to direction (i.e.,transmission direction), e.g., for an uplink (UL), the communicationdevice is the transmitter and the network is the receiver, and for adownlink (DL), the network is the transmitter and the communicationdevice is the receiver.

FIG. 2 is a schematic diagram of a communication device 20 according toan example of the present invention. The communication device 20 may bea communication device or the network shown in FIG. 1, but is notlimited herein. The communication device 20 may include a processingcircuit 200 such as a microprocessor or Application Specific IntegratedCircuit (ASIC), a storage device 210 and a communication interfacingdevice 220. The storage device 210 may be any data storage device thatmay store a program code 214, accessed and executed by the processingcircuit 200. Examples of the storage device 210 include but are notlimited to a subscriber identity module (SIM), read-only memory (ROM),flash memory, random-access memory (RAM), hard disk, optical datastorage device, non-volatile storage device, non-transitorycomputer-readable medium (e.g., tangible media), etc. The communicationinterfacing device 220 includes at least one transceiver transmittingand receiving signals (e.g., data, messages and/or packets) according toprocessing results of the processing circuit 200.

In the following embodiments, a UE is used to represent a communicationdevice in FIG. 1, to simplify the illustration of the embodiments.

A radio access network (RAN)-involved codec adaptation solution enablesan eNB to transmit a UL or DL codec adaptation indication with anexplicitly recommended bit-rate information to help a UE to select oradapt a proper codec rate for a voice over long term evolution/5G(LTE/5G) (VoLTE/5G) or video over LTE/5G (ViLTE/5G). In one example,when an eNB determines to recommend the UE in a RRC CONNECTED mode tomodify a bit rate due to a poor radio condition or a network congestiondetected in the UL or the DL, the eNB may signal a bit raterecommendation indicating a recommended bit rate (or recommended codecrate) to the UE.

A scenario assumed according to an example of the present invention isstated as follows. A UE may receive and apply a bit rate recommendation(e.g., indicating a low codec rate) from a first BS. Then, the UEreceives a handover command from the first BS, and performs a handoverto a second BS according to the handover command. After performing thehandover to the second BS, the UE keeps using the low codec rate.However, it is not beneficial to keep using the low codec rate, if thesecond BS is able to serve the UE with a codec rate higher than the lowcodec rate. In this situation, the UE is not able to have a bettervoice/video quality after performing the handover.

FIG. 3 is a flowchart of a process 30 according to an example of thepresent invention. The process 30 can be utilized in a UE, forperforming a codec rate adaptation. The process 30 includes thefollowing steps:

Step 300: Start.

Step 302: Receive a first bit rate recommendation from a first cell.

Step 304: Select a first codec rate according to the first bit raterecommendation and encode a first plurality of packets according to thefirst codec rate.

Step 306: Receive a handover command configuring the UE to hand over toa second cell from the first cell.

Step 308: Perform a handover to the second cell in response to thehandover command.

Step 310: Transmit a bit rate query to the second cell after performingthe handover.

Step 312: Receive a second bit rate recommendation from the second cell,wherein the second cell transmits the second bit rate recommendation inresponse to the bit rate query.

Step 314: Select a second codec rate according to the second bit raterecommendation and encode a second plurality of packets according to thesecond codec rate.

Step 316: End.

According to the process 30, the UE selects (or determines) a secondcodec rate according to the second bit rate recommendation and encodes asecond plurality of packets according to the second codec rate after thehandover. That is, if the second cell can serve a codec rate higher thanthe first codec rate, the UE may not keep using the first codec rateafter performing the handover. The UE may select the second codec rate,and encode the second plurality of packets more efficiently.

Realization of the process 30 is not limited to the above description.The following examples may be applied to the process 30.

In one example of the step 310, the UE transmits the bit rate query tothe second cell, when the handover command configures the codec rateadaptation. The UE does not transmit the bit rate query to the secondcell, when the handover command does not configure the codec rateadaptation (e.g., the second cell does not support the codec rateadaptation, so the second cell does not transmit the bit raterecommendation). In this case, the UE may change the codec rateaccording to its determination, after (or when) performing the handover(or in response to the handover). In one example, the UE may determineto increase the first codec rate without receiving the second bit raterecommendation, after (or when) performing the handover (or in responseto the handover) in order to obtain a better voice/video quality (e.g.,when a channel quality indicator or a signal strength/quality of thesecond cell is good (e.g., above a threshold)).

A scenario assumed according to an example of the present invention isstated as follows. A UE may receive and apply a bit rate recommendation(e.g., indicating a low codec rate) from a first cell. Then, the UEperforms a Radio Resource Control (RRC) connection reestablishmentprocedure due to a detection of a radio link failure. The UEreestablishes a connection to a second cell. After the RRC connectionreestablishment procedure, the UE keeps using the low codec rate.However, it is not beneficial to keep using the low codec rate if thesecond cell is able to serve the UE with a codec rate higher than thelow codec rate. The UE is not able to have a better voice/video qualityafter the RRC connection reestablishment procedure.

FIG. 4 is a flowchart of a process 40 according to an example of thepresent invention. The process 40 can be utilized in a UE, forperforming a codec rate adaptation. The process 40 includes thefollowing steps:

Step 400: Start.

Step 402: Receive a first bit rate recommendation from a first cell.

Step 404: Select a first codec rate according to the first bit raterecommendation and encode a first plurality of packets according to thefirst codec rate.

Step 406: Detect a radio link failure on the first cell.

Step 408: Perform a RRC connection reestablishment procedure to a secondcell in response to the radio link failure.

Step 410: Transmit a bit rate query to the second cell, after performingthe RRC connection reestablishment procedure.

Step 412: Receive a second bit rate recommendation from the second cell,wherein the second bit rate recommendation is transmitted by the secondcell in response to the bit rate query.

Step 414: Select a second codec rate according to the second bit raterecommendation and encode a second plurality of packets according to thesecond codec rate.

Step 416: End.

According to the process 40, if the second cell can serve a codec ratehigher than the first codec rate, the UE may not keep using the firstcodec rate after (or when) performing the RRC connection reestablishmentprocedure (or in response to the RRC connection reestablishmentprocedure). The UE may select the second codec rate, and encode thesecond plurality of packet more efficiently.

Realization of the process 40 is not limited to the above description.The following examples may be applied to the process 40.

In one example of the step 410, the UE transmits the bit rate query tothe second cell, when receiving a RRC message (e.g.,RRCConnectionReconfiguration) following the RRC connectionreestablishment procedure. The RRC message configures the codec rateadaptation. The UE does not transmit the bit rate query to the secondcell, when the RRC message does not configure the codec rate adaptation.In this case, the UE changes the codec rate according to itsdetermination, after (or when) performing the RRC connectionreestablishment procedure (or in response to the RRC connectionreestablishment procedure). In one example, the UE determines toincrease the first codec rate without receiving the second bit raterecommendation after the RRC connection reestablishment procedure inorder to obtain a better voice/video quality (e.g., when a channelquality indicator or a signal strength/quality of the second cell isgood (e.g., above a threshold)).

In one example of the step 410, the UE transmits the bit rate query tothe second cell, when receiving a RRCConnectionReestablishment messageof the RRC connection reestablishment procedure. TheRRCConnectionReestablishment message configures the codec rateadaptation. The UE does not transmit the bit rate query to the secondcell, when the RRCConnectionReestablishment message does not configurethe codec rate adaptation. In this case, the UE changes the codec rateaccording to its determination, after the RRC connection reestablishmentprocedure.

The following examples may be applied to the processes 30 and 40.

A BS may transmit the second bit rate recommendation in/via the secondcell in response to the handover or the RRC connection reestablishmentprocedure without receiving the bit rate query. The UE may not need totransmit the bit rate query during/after the handover or the RRCconnection reestablishment procedure.

A scenario assumed according to an example of the present invention isstated as follows. A UE may frequently transmit the bit rate query tothe network such that the network has to frequently respond the bit ratequery, which causes a waste of radio resources.

FIG. 5 is a flowchart of a process 50 according to an example of thepresent invention. The process 50 can be utilized in a UE, forperforming a codec rate adaptation. The process 50 includes thefollowing steps:

Step 500: Start.

Step 502: Transmit a bit rate query to a cell of a BS.

Step 504: Retransmit the bit rate query to the cell, when not receivinga response for responding to the bit rate query within a time period.

Step 506: End.

According to the process 50, the UE does not frequently transmit the bitrate query to the network. The UE retransmits the bit query if thenetwork does not respond to the bit rate query within the time period.Thus, the radio resources can be saved.

Realization of the process 50 is not limited to the above description.The following examples may be applied to the process 50.

In one example, the time period is configured by a network of the cell.In one example, the response is a bit rate recommendation or a rejectresponse for rejecting the bit rate query for a recommended bit rate.

A scenario assumed according to an example of the present invention isstated as follows. When the UE is triggered to transmit a first MediumAccess Control (MAC) Control Element (CE) for the bit rate query, the UEmay also be triggered to transmit at least one second MAC CE. Or theremay be data for the UE to transmit. If there is no sufficient resourceto transmit all of the first MAC CE, the at least one second MAC CE anddata, it is not known which one the UE should transmit first (i.e., thetransmitting priorities of the first MAC CE, the second MAC CE and thedata are unknown).

FIG. 6 is a flowchart of a process 60 according to an example of thepresent invention. The process 60 can be utilized in a UE, forperforming a codec rate adaptation. The process 60 includes thefollowing steps:

Step 600: Start.

Step 602: Trigger a first transmission of a first MAC CE for a bit ratequery or a delay budget reporting, and a second transmission of a data.

Step 604: Make a first determination that a transmission priority of thefirst MAC CE is lower than a transmission priority of the data.

Step 606: Include the data in a MAC Protocol Data Unit (PDU) in responseto the first determination.

Step 608: Include the first MAC CE in the MAC PDU in response to thefirst determination, if a remaining space in the MAC PDU is sufficientfor allocating the first MAC CE after allocating the data.

Step 610: Transmit the MAC PDU to a BS.

Step 612: End.

According to the process 60, the UE makes the determination of which oneof the first MAC CE and the data should be transmitted first. Accordingto the determination, the UE first includes (e.g., allocates) the datain the MAC PDU since the priority of the data is higher than that of thefirst MAC CE. The UE then includes the first MAC CE in the MAC PDU if(or when) there is sufficient remaining space in the MAC PDU.

Realization of the process 60 is not limited to the above description.The following examples may be applied to the process 60.

In one example, the UE triggers a third transmission of a second MAC CE(e.g., buffer status report MAC CE). Then, the UE makes a seconddetermination that a transmission priority of the second MAC CE ishigher than a transmission priority of the data. The UE includes thesecond MAC CE in the MAC PDU in response to the second determination. Ifa remaining space in the MAC PDU is sufficient for including the dataafter including the second MAC CE, the UE includes the data in the MACPDU. If the remaining space in the MAC PDU is sufficient for includingthe first MAC CE after including the second MAC CE and the data, the UEincluding the first MAC CE in the MAC PDU.

In one example, the data is obtained by the UE from any logical channelexcept a UL common control channel (UL-CCCH).

When data is obtained from the UL-CCCH, the UE determines the data fromthe UL-CCCH has a higher priority than the second MAC CE. In response tothe determination, the UE includes the data in the MAC PDU firstly, thesecond MAC CE secondly, and the first MAC CE lastly.

The following examples may be applied to the processes 30, 40, 50 and60.

In one example, the first cell and the second cell belong to the same BSor different BSs (e.g., the first BS and the second BS) in the network.In one example, a codec of the first codec rate and the second codecrate is an Automatic Multi-Rate (AMR) codec, an AMR Wideband (AMR-WB)codec or an Enhanced Voice Services (EVS) codec. When the first codecrate is changed, the codec may or may not be changed.

In one example, the first plurality of packets and the second pluralityof packets are voice packets belonging to a first voice call (e.g.,Internet Protocol Multimedia Subsystem (IMS) voice call). In oneexample, the first plurality of packets and the second plurality ofpackets are IMS video packets belonging to a second video call (e.g.,IMS video call). The UE transmits the encoded first plurality of packetsand the encoded second plurality of packets to the second cell.

In one example, the bit rate query, the first bit rate recommendationand the second bit rate recommendation are MAC CEs. In one example, thebit query, the first rate recommendation and the second raterecommendation are RRC messages.

In one example, before the step 302, the step 402 or the step 502, theUE transmits a first RRC message including an indication indicating to anetwork (e.g., a BS) that the UE supports codec rate adaptation. Then,the UE receives a second RRC message which configures the UE to applythe codec rate adaptation from the network. The first cell of thenetwork transmits the second RRC message in response to the first RRCmessage. The network transmits the second RRC message when the networkknows the UE supports the codec rate adaptation, and the networkconfigures a bearer which has Quality of Service (QoS) setting (e.g.,QoS class identifier, QCI) for a voice call or a video call to the UE.The UE transmits the bit rate query, and processes the bit raterecommendation in the MAC CE in response to the second RRC message. TheMAC layer of the UE does not apply the bit rate recommendation, when theUE does not receive the second RRC message. In one example, the firstRRC message is a UECapabilityInformation message, and the second RRCmessage is a RRCConnectionReconfiguration message. In one example, ifthe UE is configured by the network more than one MAC entities, the UEapplies the MAC entity which is responsible for transmitting thevoice/video packets (e.g., the first plurality of packets and the secondplurality of packets in the processes 30 and 40) to transmit the bitrate query and process the bit rate recommendation. In one example, thesecond RRC message specifically configures the codec rate adaptation toa specific MAC entity so the UE knows that the specific MAC entity isused to transmit the bit rate query and process the bit raterecommendation. That is, the codec rate adaptation configuration isassociated to a MAC entity configuration.

In one example, the UE receives the codec rate adaptation configurationin a RRC connected state. The UE releases the codec rate adaptationconfiguration, when the UE enters the RRC idle state from the RRCconnected state. The UE keeps the codec rate adaptation configuration,when the UE is configured by the network to suspend its RRC connection(called RRC suspended state) or when the UE is configured to enter a RRClightly connected state (or called a RRC inactive state). Thus, the UEtransmits the bit rate query and processes the bit rate recommendation,when the UE enters the RRC connected state from the RRC suspended stateor from the RRC lightly connected state.

In one example, when a MAC CE is allocated, its corresponding subheaderis also allocated. Thus, the UE considers whether the remaining space inthe MAC PDU is sufficient for the MAC CE or not. The UE considers theremaining space is sufficient to allocate the MAC CE and thecorresponding subheader.

Those skilled in the art should readily make combinations, modificationsor alternations on the abovementioned description and examples. Any ofthe abovementioned description, steps or processes including suggestedsteps can be realized by means that could be hardware, software,firmware, an electronic system, or combination thereof. An example ofthe means may be the communication device 20. Any of the above processesand examples above may be compiled into the program code 214.

To sum up, the present invention provides a device and a method for acodec rate adaptation. The UE is able to select a codec rate that makesthe process of codec more efficiently. Thus, the problem in the art issolved.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A communication device for performing a codecrate adaptation, comprising: a storage device, for storing instructionsof: receiving a first bit rate recommendation from a first cell;selecting a first codec rate according to the first bit raterecommendation and encoding a first plurality of packets according tothe first codec rate; receiving a handover command configuring thecommunication device to hand over to a second cell from the first cell;performing a handover to the second cell in response to the handovercommand; transmitting a bit rate query to the second cell when thehandover command configures the codec rate adaptation; receiving asecond bit rate recommendation from the second cell, wherein the secondcell transmits the second bit rate recommendation in response to the bitrate query; selecting a second codec rate according to the second bitrate recommendation and encoding a second plurality of packets accordingto the second codec rate; and not transmitting the bit rate query to thesecond cell, when the handover command does not configure the codec rateadaptation; and a processing circuit, coupled to the storage device,configured to execute the instructions stored in the storage device. 2.The communication device of claim 1, wherein the storage device furtherstores the instruction of: determining to increase the first codec ratewithout receiving the second bit rate recommendation, after performingthe handover.
 3. The communication device of claim 1, wherein the firstcell and the second cell belong to the same base station (BS) ordifferent BSs.
 4. The communication device of claim 1, wherein a codecof the first codec rate and the second codec rate is an AutomaticMulti-Rate (AMR) codec, an AMR Wideband (AMR-WB) codec or an EnhancedVoice Services (EVS) codec.
 5. The communication device of claim 1,wherein the first plurality of packets and the second plurality ofpackets are voice packets belonging to a first voice call, or InternetProtocol Multimedia Subsystem (IMS) video packets belonging to a secondvideo call.
 6. The communication device of claim 1, wherein the bit ratequery, the first bit rate recommendation and the second bit raterecommendation are Medium Access Control (MAC) Control Elements (CEs) orRadio Resource Control (RRC) messages.
 7. A method for a communicationdevice to perform a codec rate adaptation, comprising: the communicationdevice receiving a first bit rate recommendation from a first cell; thecommunication device selecting a first codec rate according to the firstbit rate recommendation and encoding a first plurality of packetsaccording to the first codec rate; the communication device receiving ahandover command configuring the communication device to hand over to asecond cell from the first cell; the communication device performing ahandover to the second cell in response to the handover command; thecommunication device transmitting a bit rate query to the second cellwhen the handover command configures the codec rate adaptation; thecommunication device receiving a second bit rate recommendation from thesecond cell, wherein the second cell transmits the second bit raterecommendation in response to the bit rate query; the communicationdevice selecting a second codec rate according to the second bit raterecommendation and encoding a second plurality of packets according tothe second codec rate; and the communication device not transmitting thebit rate query to the second cell, when the handover command does notconfigure the codec rate adaptation.
 8. The method of claim 7, furthercomprising: the communication device determining to increase the firstcodec rate without receiving the second bit rate recommendation, afterperforming the handover.
 9. The method of claim 7, wherein the firstcell and the second cell belong to the same base station (BS) ordifferent BSs.
 10. The method of claim 7, wherein a codec of the firstcodec rate and the second codec rate is an Automatic Multi-Rate (AMR)codec, an AMR Wideband (AMR-WB) codec or an Enhanced Voice Services(EVS) codec.
 11. The method of claim 7, wherein the first plurality ofpackets and the second plurality of packets are voice packets belongingto a first voice call, or Internet Protocol Multimedia Subsystem (IMS)video packets belonging to a second video call.
 12. The method of claim7, wherein the bit rate query, the first bit rate recommendation and thesecond bit rate recommendation are Medium Access Control (MAC) ControlElements (CEs) or Radio Resource Control (RRC) messages.
 13. Acommunication device for performing a codec rate adaptation, comprising:a storage device, for storing instructions of: receiving a first bitrate recommendation from a first cell; selecting a first codec rateaccording to the first bit rate recommendation and encoding a firstplurality of packets according to the first codec rate; detecting aradio link failure on the first cell; performing a RRC connectionreestablishment procedure to a second cell in response to the radio linkfailure; receiving a RRC message following the RRC connectionreestablishment procedure; transmitting a bit rate query to the secondcell when the RRC message configures the codec rate adaptation;receiving a second bit rate recommendation from the second cell, whereinthe second cell transmits the second bit rate recommendation in responseto the bit rate query; and selecting a second codec rate according tothe second bit rate recommendation and encoding a second plurality ofpackets according to the second codec rate; and not transmitting the bitrate query to the second cell, when the RRC message does not configurethe codec rate adaptation; and a processing circuit, coupled to thestorage device, configured to execute the instructions stored in thestorage device.
 14. The communication device of claim 13, wherein thestorage device further stores the instruction of: determining toincrease the first codec rate without receiving the second bit raterecommendation, after performing the handover.
 15. The communicationdevice of claim 13, wherein the first cell and the second cell belong tothe same base station (BS) or different BSs.
 16. The communicationdevice of claim 13, wherein a codec of the first codec rate and thesecond codec rate is an Automatic Multi-Rate (AMR) codec, an AMRWideband (AMR-WB) codec or an Enhanced Voice Services (EVS) codec. 17.The communication device of claim 13, wherein the first plurality ofpackets and the second plurality of packets are voice packets belongingto a first voice call, or Internet Protocol Multimedia Subsystem (IMS)video packets belonging to a second video call.
 18. The communicationdevice of claim 13, wherein the bit rate query, the first bit raterecommendation and the second bit rate recommendation are Medium AccessControl (MAC) Control Elements (CEs) or Radio Resource Control (RRC)messages.